Pym was born in England where he studied fine art in London. During the 1930s Pym's work covered everything from portraits and illustrations for London weekly and national daily newspapers, to design commissions from major companies, such as the Ford Motor Company, to portray their products.

During the Second World War Pym produced what have been described as ‘famous morale-boosting posters' for the Ministry of Information. Shortly after the war, Pym emigrated to Canada, settling in Vancouver.

In 1970, Harold was commissioned by the British Columbia Government to go to Osaka, Japan and create art for their Pavilion at the World's Fair. Whilst living in Vancouver, Harold's work included murals and guest room pictures for major hotel chains.